In optical communications, it is often necessary to have a wavelength filter device that is capable of selecting a specific optical transmission having one or more particular wavelengths from a plurality of wavelengths within a light wave spectrum.
Typically, specific wavelengths within the light wave spectrum are separated out using a thin film filter, a holographic Bragg reflector (HBR), or an array waveguide grating (AWG). A problem with conventional thin film filters, holographic Bragg reflectors, and array waveguide grating devices is that they are manufactured and designed to separate one or more particular wavelengths, i.e. these wavelength filter devices are tuned to specific wavelengths.
In many applications it is often advantageous for the wavelength filter device to be customizable so that different wavelengths can be selected or deselected depending on the desired wavelengths for the particular application. One conventional solution to this problem is a device that contains multiple thin film filter devices that are mechanically rotated to separate out specific wavelengths of the light wave spectrum. Another known solution is a device that separates all wavelengths within a light wave spectrum and uses a cascade of optical switches or attenuators to select the appropriate wavelengths. However, a problem with these wavelength filter devices is that they are typically much larger in size, are more expensive, are less reliable and consume more power than a typical holographic Bragg reflector device or array waveguide grating device.